PC World magazine is celebrating 20 years of publication with its March issue and it’s a compelling reminder of how much personal computing has changed during the past two decades.

Twenty years ago, personal computers were still very much a hobby item, with many, many companies producing the machines themselves, peripherals and software. That was easy to see in the “plop” factor of computing magazines of the time. The inaugural issue of PC World was a 324-page heavyweight. Its archrival PC Magazine ran to hundreds of pages, and when not being used as a magazine, made an adequate doorstop.

The anniversary issue of PC World runs to 166 pages, and the current issue of PC Magazine is even less. The focus is less hobby than business. That’s not surprising, since recent census data says almost six of 10 of us use a personal computer every working day.

The machines themselves have changed a lot. Twenty years ago, the machine had a bay for a 5.25-inch floppy disk and one for the newfangled 3.25 floppy.

Today, Dell is shipping computers without a floppy drive, which makes sense. It’s been years since any major software was installed from anything but a CD-ROM, and little, solid-state thumb-sized USB drives handle any need to pocket data, with 256-megabyte capacity that exceeds that of entire systems when PC World was born.

PC World gave no coverage in its first few issues to Microsoft Windows — mostly because Windows 1.0 wouldn’t appear until 1984 and wouldn’t really take off until the ’90s. That it debuted in 1984 and later became the Big Brother of computing must give some satisfaction to George Orwell, whose novel, titled with that year, dealt with a vast, ubiquitous, totalitarian government. When Windows did debut, PC World said it “should have a lasting effect on the entire personal computer industry.”

On the other hand, the magazine had predicted that pen-based computing would replace the keyboard, but hey, you can’t always be right.

The IBM XT machines of the day were running at 4.77 megahertz. Today’s ordinary stuff swishes by at 2.4 gigahertz. And, of course, high-end machines cost several thousand dollars. Today’s machines that would outperform by several multiples anything available then are selling for less than $1,000.

Memory was expensive then and machines shipped with 128 kilobytes of RAM. Today they ship with 512 megabytes of RAM, more storage capacity than the 1983 systems, including hard drive.

The March issue of PC World is chock full of these memory-lane tidbits, and if you’ve been following computers for more than 20 years as some of us gezzer-geeks have done, the nostalgia is worth the $6.99 cover price. You also can find some of it online at www.pcworld.com.